linux-imx

gpio: mxc: Add PAD wakeup support for SoCs with SCU

This patch enables gpio pin's pad wakeup function which
is supported by SCFW, with pad wakeup enabled, GPIO's
power is no need to be enabled after suspend, hence
save a sub-system's power.

To enable pad wakeup, dtb needs to provide pad wakeup
number for each gpio port, and each pin has to provide
<pin_id, type, line>, they should be inside each gpio node,

To enable pad wakeup, dtb needs to provide pad wakeup
number for each gpio port, and each pin has to provide
<pin_id, type, line>, they should be inside each gpio node,
this is for calling SCFW APIs to enable/disable pad wakeup,
example of adding GPIO4_22 pad wakeup in dtb:

&lsio_gpio4 {
    /* total pad wakeup number in gpio4 */
    pad-wakeup-num = <1>;
    /* SC_P_USDHC1_CD_B, SC_PAD_WAKEUP_LOW_LVL, LINE 22 */
    pad-wakeup = <27 4 22>;
};

Pad wakeup will be enabled after GPIO port suspend, and
once any pad wakes up system, gpio driver will get the
wakeup line and handles the event during noirq resume
phase.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>